There are thousands of kidney transplant candidates annually who have an incompatible living donor. These sensitized patients have several options available to them: wait on the deceased donor (DD) kidney wait list, attempt kidney-paired donation (KPD), or undergo incompatible living donor kidney transplantation (ILDKT). Limited clinical evidence exists to identify the best of these options for individual patients. While waiting for a DD kidney has the advantage of potentially providing a fully compatible kidney, it is currently unknown how long sensitized patients remain on the DD waiting under the new kidney allocation system. Historically, waiting times can approach 5-7 years, and mortality while on the waiting list averages 5- 10% per year. Similarly, KPD exchanges can provide a compatible kidney for a recipient; however, less than half of all patients who attempt KPD exchange will find a match. For those who are highly HLA sensitized or have a blood type that is difficult to match, the KPD match rate is even lower. ILDKT leverages the patient?s existing donor and does not require waiting for a match, but the benefit of ILDKT is not uniform, as the higher a patient?s sensitization, the less beneficial ILDKT is. This proposal will generate a by which clinicians can identify the most beneficial of these three options for individual patient phenotypes. To accomplish this, we will utilize Scientific Registry of Transplant data to examine how long it takes sensitized patients to receive a DD kidney transplant. We will also utilize National Kidney Registry data to identify at what rate sensitized patients receive a kidney through KPD exchanges. With this information, we will build a Markov model to answer the critical clinical question: what should a specific patient with an incompatible donor do in order to optimize survival after kidney transplantation? We hypothesize that there will be certain phenotypes of patients for which ILDKT is the best treatment option, but also phenotypes for which ILDKT is less beneficial than either remaining on the DD waiting list or entering a KPD registry. Being able to identify the optimal treatment strategy for phenotypically unique patients would be immediately clinically applicable and could improve the quality of care for the thousands of patients awaiting kidney transplantation who have an incompatible living donor. By performing this research, Dr. Jackson will receive the rigorous training in epidemiology, research methodology, and decision process modeling necessary to become a skilled surgeon-scientist and a leader in transplant surgery.